1. Field of the Invention
The present invention is related to the primers for diagnosis of one or more kinds of cancers and a diagnostic kit containing the above primers, particularly to common primers that can simultaneously detect six MAGE sub-types from MAGE 1 to MAGE 6 (MAGE 1–6) or eight GAGE sub-types from GAGE 1 to GAGE 8 (GAGE 1–8) and a diagnostic kit containing the above common primers.
2. Description of the Prior Art
The diagnosis of cancers has been accomplished through the medical physical examination, X-ray and CT, histological examination, etc. However, these methods have not been appropriate for discrimination of a cancer among a cancer at its initial stage, a minute cancer, and a benign tumor.
However, the molecular biological diagnostic methods that have been developed recently have contributed greatly to the development of the cancer diagnostic area owing to their specificity in the diagnosis of cancers and their high sensitivity The most widely used method among many molecular biological diagnostic methods is the polymerase chain reaction (PCR) or the reverse transcriptase-polymerase chain reaction (RT-PCR). The abnormal gene, cancerous antigen gene, etc. of a sample are amplified and detected in these methods.
Particularly, RT-PCR is a method of detecting mRNA which is expressed in a particular gene. It may be used for the diagnosis of a cancer by examining the property of expression of cancerous antigen genes. The most important matter in the diagnosis of a cancer in the RT-PCR method is selection of a target gene for cancer diagnosis to be detected (hereinafter referred to as a “cancer diagnosis marker”). Generally, one cancer diagnosis marker is detected.
The requirements for a cancer diagnosis marker are that it should be expressed specifically in the cancer and that in a large amount in as many as possible cancers. MAGE (melanoma antigen gene) and GAGE are two kinds of cancer-associated testis antigens that are expressed in many kinds of cancer tissues but are not expressed in normal tissues except for the testis. It has been clarified that MAGE has been expressed in many cancers such as the stomach cancer (1, 2), esophagus cancer (3), colon cancer (4), lung cancer (5), breast cancer (6, 7), liver cancer (8), leukemia (9), neuroblastoma (10), ovary cancer (11), etc. in many studies since it was discovered in the melanoma. And it has been reported that GAGE has been expressed in the melanoma, sarcoma, small-cell carcinoma, head and neck cancer, bladder cancer, ovary cancer, etc. (11, 12). Therefore, MAGE and GAGE are very extensively utilized as cancer diagnostic markers since not only they can detect many kinds of cancers, not a simple kind of cancer, but also they have a high specificity for expression of cancer tissues compared to other cancer-associated antigens such as the carcinoembryonic antigen, etc. Also, MAGE and GAGE have a high homogeneity of genes among sub-types. About 12 kinds of sub-types of MAGE have the homogeneity ranging from about 56% to 99%, and 8 kinds of sub-types of GAGE have the homogeneity ranging from about 82% to 99%. Therefore, it is possible to increase the cancer diagnosis rate by using such same DNA sequence part as a primer since many sub-types of MAGE or GAGE may be detected simultaneously during RT-PCR.
Accordingly, common primers having a high cancer diagnostic rate and a high cancer diagnosis specificity through selection of MAGE or GAGE as a marker for cancer diagnosis and simultaneous detection of many sub-types of the marker for cancer diagnosis by RT-PCR are suggested in the present invention.